Figure 1

From: CD99 ligation upregulates HSP70 on acute lymphoblastic leukemia cells and concomitantly increases NK cytotoxicity

Figure 1

CD99 ligation increases HSP70 expression in CD99-positive human B and T lymphocytes. (a) Time-dependent upregulation of cytoplasmatic (cy) HSP70 in Reh cells: cells were cultured for the indicated time in the presence of 10 μg/ml of CD99 mAbs (DN16, O662 and hec2), MOPC1 (control mAb) or without treatment (control). Annexin V and 7AAD were used to stain apoptotic and dead cells. In all performed experiments, HSP70 was measured on non-apoptotic cells. Error bars indicate S.E.M. of triplicate wells. Data represent six independent experiments. (b) HSP70 upregulation is a specific response upon CD99 ligation in Reh cells: cells were treated with the indicated mAbs for 3 h. Strong surface (s) HSP70 upregulation was observed in CD99-highly expressing Reh and Jurkat cell lines. CD99-low expressing Raji and CD99-negative murine El4 cells did not exhibit HSP70 response when incubated with DN16. Error bars show S.E.M. of three independent experiments. Surface HSP70 expressions were normalized to untreated control and are shown as x-fold induction. (c) Cytoplasmatic and surface HSP70 expression in BCP-ALL cases (P<0.01). (d) Correlation of CD99 at diagnosis with induced (s) (P1<0.02) and (cy) (P2<0.05) HSP70 (3 h) is shown. Primary BCP-ALL samples (n=21) were incubated with DN16 mAb for 3 h, induced (s) and (cy) HSP70 were detected with anti-HSP70 Ab. (e) Representative HSP70 staining of primary patient BCP-ALL sample: flow cytometric analysis of HSP70 expression on leukemia cells incubated for 3 h with DN16 mAbs (red line), MOPC1 (blue line) or isotype control (black dashed line). HSP70 was detected either with HSP70-FITC from ‘Stressgen’ (HSP70*) or with unconjugated HSP70 Ab followed by secondary step antibody conjugated with PE (HSP70**)